In recent years, flat-panel displays have been utilized in various products and fields, and have been required to be larger in size, higher in image quality, and lower in power consumption.
Under such circumstances, an organic EL display device including an organic EL element utilizing the electroluminescence (hereinafter abbreviated as “EL”) of an organic material has attracted a great deal of attention as a flat-panel display which is of an all-solid type and which is excellent in low-voltage driving, high-speed responsiveness, self-luminous property, etc.
An organic EL display device is for example constituted by a substrate made of glass or the like, TFTs (thin-film transistor) provided on the substrate, and organic EL elements connected to the TFTs.
An organic EL element is a light-emitting element capable of emitting high-intensity light by low-voltage direct-current driving, and has a structure in which a first electrode, an organic EL layer, and a second electrode are stacked in this order. Among them, the first electrode is connected to a TFT. Further, provided as the EL organic layer between the first electrode and the second electrode is an organic layer obtained by stacking a positive-hole injection layer, a positive-hole transport layer, an electron blocking layer, a light emitting layer, a positive-hole blocking layer, an electron transport layer, an electron injection layer, etc.
In general, a full-color organic EL display device has an array of red (R), green (G), and blue (B) organic EL elements formed as subpixels on a substrate, and displays an image by selectively causing these organic EL elements to emit light at a desired luminance.
In the manufacture of such an organic EL display device, a light-emitting layer composed of organic light-emitting materials that emit their respective colors of light is formed as a pattern for each organic EL element serving as a light-emitting element.
Known as a method for forming a light-emitting layer as a pattern in this manner is for example a vacuum deposition method using a mask for use in vapor deposition mask that is referred to as a shadow mask (e.g., see Patent Literature 1).
In such a case where an organic EL display device is manufactured with use of vacuum deposition, a larger substrate size means, in general, that the number of panels that can be formed from a single substrate is larger and the cost of each single panel is lower. For this reason, use of a lager-sized substrate allows an organic EL display device to be manufactured at lower cost.
Accordingly, Patent Literature 1 discloses a method for, by using a vapor deposition mask that is smaller in size than a film formation substrate on which a film is to be formed and carrying out vapor deposition while moving the vapor deposition mask and a vapor deposition source relative to the film formation substrate, forming a vapor-deposited film on the film formation substrate of a large size.
(a) of FIG. 27 is a plan view schematically showing a vapor deposition apparatus described in Patent Literature 1, and (b) of FIG. 27 is a cross-sectional view of the vapor deposition apparatus taken along an arrow shown in (a) of FIG. 27.
As shown in (a) and (b) of FIG. 27, a vapor deposition apparatus 310 described in Patent Literature 1 includes a vapor deposition source 311, a vapor deposition source container 312 in which the vapor deposition source 311 is stored, a ball screw 313 to which the vapor deposition source container 312 is assembled, a liner guide 314 along which the vapor deposition source container 312 can move along the major axis of the ball screw 313 as the ball screw 313 rotates on its axis.
Provided on top of the vapor deposition source container 312 is a mask holding part 315, with a vapor deposition mask 316 fixed to the mask holding part 315.
A film formation substrate 200 on which a film is to be formed is held by a substrate holding part 318 in such a manner as to have its vapor deposition surface facing the vapor deposition source 311.
The vapor deposition source 311 and the vapor deposition mask 316 are moved relative to the film formation substrate 200 by moving together along the major axis of the ball screw 313 as the rotation of the ball screw 313 causes the vapor deposition source container 312 to move.